Coating of articles

ABSTRACT

Plastic containers are given a coating of barrier or other coating material by being passed in close proximity to the lower edge of a plate curved downwardly. Liquid coating material is delivered to the back of the plate, to spread over it and fall as a curtain through which the article is passed, the article being rotated to present the whole of its recipient surface to the curtain. The articles may be tilted as they pass through the curtain.

This invention relates to methods and apparatus for the coating ofarticles such as, by way of non-limiting example, hollow, rigid orsemi-rigid containers, by application of a liquid coating material tothe articles, the coating material being subsequently dried or allowedto dry. In respect of the apparatus, the invention further relates toholders for carrying the articles through the apparatus.

The invention is typically but without limitation, concerned with thecoating of packaging containers made of polymers such as polyethyleneterephthalate (PET), by application of a coating material to enhance thebarrier properties of the containers. By "barrier properties" we meanpartly the ability of the container to resist ingress, through itswalls, of air or other gases, microorganisms or spores ofmicro-organisms, the object generally being to protect a food or otherproduct subsequently packed in the container from spoilage by oxidationor microbial action for a period sufficiently long to give the product adesired shelf-life. The term "barrier properties" equally means theability of the container to contain products pressurised above theambient pressure, such as carbonated beverages, or foods or drinkspacked under aseptic (sterile) conditions so that the internal pressurewill not be significantly reduced, or (in the latter case) the sterilityof the contents will not be contaminated from the atmosphere outside thecontainer.

Coatings applied by the method or by the apparatus of this invention mayhave the further or alternative purpose of decoration, for example byproviding a coloured opaque or transparent surface.

According to the invention in a first aspect, a method of applying acoating over a non-horizontal recipient surface of an article, comprisesthe steps of:

directing a supply of liquid coating material against a back surface ofa curtain plate so as to spread the liquid over the back surface to fallas curtain from a lower edge of the curtain plate;

effecting continuous relative movement as between the article and thecurtain plate, with the article closely in front of the curtain plate,such that the recipient surface intersects the curtain;

allowing the material to run freely down the recipient surface andallowing excess material to drain freely from it; and

causing the coating so applied to dry on the recipient surface.

Where the method is used for coating an external recipient surface whichextends around the article, the step of effecting relative movementpreferably comprises simultaneously causing the recipient surface tointersect the curtain and effecting relative rotation as between thecurtain plate and the article, so as to present the recipient surfaceprogressively to the curtain.

Where the method is used for coating an external recipient surface whichextends axisymmetrically around an article defining a central axis, thestep in which the recipient surface intersects the curtain is preferablycarried out with the central axis inclined to the vertical.

The step of effecting relative movement as between the article and thecurtain plate may be carried out with an upper portion of at least thatpart of the recipient surface facing the curtain plate located above thelevel of the lower edge of the curtain plate so that the upper portiondoes not intersect the curtain. The method then preferably includes thefurther step of applying a band of coating material over the upperportion of the recipient surface before or after applying a coating bymeans of the curtain.

Preferably the band is applied by the method the subject of ourco-pending U.S. patent application Ser. No. 093,565, filed July 15, 1987as a national stage applicaton of Application No. PCT/GB86/00598, filedOct. 6, 1986, claiming priority of UK patent applications. Nos. 8524517and 8614527. As applied to the method of the present invention, by wayof this additional step, the step of coating the upper portionpreferably comprises:

directing a stream of liquid coating material on to a moving donorsurface of an elongate donor member while moving the latter continuouslyalong a first path, so as to charge the donor surface with apredetermined quantity of the material; and

effecting continuous relative movement as between the recipient surfaceand the donor surface so that the latter transfers coating material onto the upper portion of the former in said band.

The said donor member may be in the form of an endless belt, the methodcomprising maintaining, while the belt is in contact with the article,both the article in its rotation and the belt in motion in said firstpath.

Preferably, the liquid coating material, both for the curtain and forcoating the upper portion of the recipient surface, is supplied from acommon source.

Excess material is preferably allowed to drain from the article todescend freely through the atmosphere directly into an open pool fromwhich it spills directly into a reservoir, the coating material beingsupplied to the curtain plate from the said reservoir.

According to the invention in a second aspect, apparatus for applyig acoating over a recipient surface of an article, comprises:

holding means for holding the article with the recipient surface in anon-horizontal attitude;

a forwardly and downwardly curved curtain plate having a generallyhorizontal, free lower edge;

nozzle means for directing a continuous supply of liquid coatingmaterial against the back surface of the curtain plate so as to spreadthe liquid over the back surface to fall as a curtain from its loweredge;

means for effectng continuous relative movement as between the articleand the curtain plate such that, with the holding means and the articleclosely in front of the curtain plate, the recipient surface willintersect the curtain when the nozzle means is operating; and

drying means for drying coating material applied to the article by itscontact with the curtain.

Preferably the apparatus includes a tilting member associated with theforward path upstream of the curtain plate, to engage the recipientsurface itself whereby to tilt the article and holding means into aninclined attitude with the central axis of the article inclined to thevertical, and a tilt guide member for co-operating with the holdingmeans for maintaining the inclined attitude throughout the advance ofthe article past the curtain plate, the holding means having a guidefollower means for cooperating with the guide member.

The tilt guide member and guide follower means are preferably sodisposed as to come into cooperation with each other only if an articleheld by the holding means has been tilted by the tilting member, so thatthe holding means fails to assume the said inclined attitude unlessholding a said article.

A modificiation may be included in the form of further guide means forengaging guide follower means on the holding means so as to deflect thelatter away from the curtain plate, the further guide means beingdownstream of the tilting member with respect to the forward path and sodisposed that it can only engage its associated guide follower means ifthe holding means has failed to be tilted by engagement of an articleheld thereby with the tilting member, the further guide means beiingarranged to keep the holding means so tilted away until it has passedthe curtain plate.

When band coating as described above is to be used, the apparatus has amain coating station at which the curtain plate is located, an auxiliarycoating station having band coating means for applying a band of coatingmaterial over an upper portion of the recipient surface not coated atthe main coating station, and transfer means for moving holding meanscarrying the article between the two stations.

According to a preferred embodiment of the invention, there is providedapparatus for coating a succession of substantially identical articles,and having a main coating station at which the curtain plate and itsnozzle are located; article-advancing means comprising an overheadconveyor arranged to be advanced at substantially constant speed, with aplurality of the holding means suspended at intervals from the conveyor,which extends through the main coating station and the drying means; anda supply system for liquid coating material, comprising the nozzle, areservoir for said material, means for supplying the nozzle from thereservoir, and return means for collecting excess coating material fromthe main coating station and from articles coated thereat.

Where there is also an auxiliary coating station, the supply system ofthe apparatus preferably comprises the nozzles at the coating stations,a reservoir for said material, means for supplying the nozzles from thereservoir, and return means for collecting excess coating material fromthe coating stations and from articles coated thereat.

The return means preferably comprises a pan for containing an open poolof coating material, the pan extending directly under that portion ofthe conveyor from which excess coating material falls from articlescarried thereby, the pan having a spillway to allow coating material tospill directly back into the reservoir.

According to the invention in a third aspect, a holder, for suspending ahollow article from an overhead conveyor, comprises a carrying head withintegral resilient fingers depending therefrom, the fingers being soarranged that when resiliently deformed they define together an endlessprofile corresponding to the profile of a portion of an article to begripped by the fingers, and a simple plunger member mounted freely inthe carrying head and reciprocable downwardly to eject the article fromthe holder.

Methods and apparatus according to the inventon in its various aspectswill now be described by way of example, with reference to theaccompanying drawings of this Application, in which:

FIG. 1 is a much-simplified front elevation of a high-speed coatingmachine for applying a barrier coating to a large succession of articlesin the form of packaging containers;

FIG. 2 is a much-simplified plan view of the machine seen in FIG. 1;

FIG. 3, again much simplified, is a sectional plan view taken on theline III--III in FIG. 4, showing the coating and draining unit of thesame machine;

FIG. 4 is a front elevation of the coating and draining unit with thefront panels (seen in FIG. 1) removed;

FIG. 5 is a diagrammatic plan, showing on a larger scale the arrangementand operation of tilting means shown in FIG. 3;

Figurse 6 to 9 are simplified views further showing the operation of thetilting means: FIGS. 6 to 8 being taken on the section planes VI--VI,VII--VII and VIII--VIII respectively in FIG. 5 and showing threesuccessive stages in the positioning of a container ready for coating,while FIG. 9 shows an empty holder as viewed from the left-hand end ofFIG. 5;

FIG. 10 is a sectional endwise elevation taken on the line X--X in FIGS.5 and 12, and shows a container being coated at the coating station;

FIG. 11 is a scrap view similar to part of FIG. 10 but showing amodification to the means whereby the container is carried through thecoating station;

FIG. 12 is an elevation as seen from the right-hand side of FIG. 10, butwith the container and its holder omitted;

FIG. 13 is an elevation, shown partly in section on the line XIII--XIIIin FIG. 14, of the holder seen in FIG. 10;

FIG. 14 is an inverted plan of the same holder;

FIG. 15 is an elevation, shown partly in section on the line XV--XV inFIG. 16, of a first alternative form of holder, designed for bottles;

FIG. 16 is an inverted plan of the holder shown in FIG. 15;

FIG. 17 shows a tubular necked article;

FIG. 18 is a somewhat diagrammatic side elevation illustrating howcontainers are stripped from their holders after being coated;

FIG. 19 is a rear view of a curtain plate in a form modified from thatshown in FIGS. 10 and 12;

FIG. 20 is an end view of the plate as seen from the left-hand side ofFIG. 19;

FIG. 21 is a simplified view corresponding with FIG. 10 but illustratinguse of the holder of FIGS. 15 and 16, the coating of a bottle, and thecoating of an untilted article;

FIG. 22 shows another modified form of curtain plate;

FIG. 23 is a simplified sectional elevation, taken on the lineXXIII--XXIII in FIG. 25, and showing a bulk tank for metering liquidcoating material;

FIG. 24 is a scrap plan view, on a larger scale, as seen in thedirection indicated at XXIV--XXIV in FIG. 23;

FIG. 25 is a sectional plan view taken on the line XXV--XXV in FIG. 23;

FIG. 26 is a simplified view similar to FIG. 9, but showing amodification in which an empty holder is tilted away from the flow ofcoating material at the coating station;

FIG. 27 corresponds with FIG. 5 but shows the modified arrangement ofcontrol rails used with the process modificiation seen in FIG. 26;

FIG. 28 is a part-sectional elevation showing a second alternative formof holder, suitable for a hollow article not having a lip or shoulderbehind which the holder can engage;

FIG. 29 is a scrap elevation showing a third alternative form of holder,for internally engaging a hollow article;

FIG. 30 is a sectional view showing the holder of FIG. 29 engaged with ahollow article;

FIG. 31 is a view similar to FIG. 30 but showing the same holder in itsrelease position;

FIG. 32 is a sectional view showing a fourth alternative form of holder,for externally engaging a flanged article, with a hollow article fullydisengaged;

FIGS. 33 to 35 are half sections showing the holder of FIG. 32,respectively about to engage with, fully engaged with, and releasing,the article;

FIG. 36 is a scrap elevation showing the holder of FIGS. 32 to 35 inoperation;

FIG. 37 is a simplified sectional scrap view showing parts of a fifthalternative form of holder, again for externally engaging a flangedarticle;

FIG. 38 is a sectional elevation showing a sixth alternative form ofholder for externally engaging a flanged article;

FIG. 39 is a modified version of the lower part of FIG. 2, showing acoating machine with an auxiliary coating station as well as the maincoating station shown in FIGS. 2 to 5;

FIG. 40 is a simplified plan view of the auxiliary coating station,drawn in the same manner as FIG. 3;

FIG. 41 is a modified version of part of FIG. 40;

FIG. 42 is a simplified plan view of the auxiliary coating station ofFIG. 40 drawn to a larger scale than FIG. 40;

FIG. 43 is a simplified elevation as seen from the bottom of FIG. 42,partly in section on the line XLIII--XLIII in FIG. 42;

FIG. 44 is a simplified sectional end elevation on the line XLIV--XLIVin FIG. 43; and

FIG. 45 is a diagrammatic and elevation relating to the modifiedauxiliary coating station of FIG. 41 and showing also a furthermodification, namely a donor belt deformable in cross-section to conformwith an irregular profile of the article being coated.

Referring to FIGS. 1 and 2, this coating machine is intended for thehigh-speed application of polyvinylidene chloride (PVdC) coatings to thecontainers 2 more clearly seen in, for example, FIGS. 10 and 18. Each ofthese containers is a cylindrical, monobloc vessel made of polyethyleneterephthalate (PET) and having an open top end bounded by a neck 4terminating in an outwardly-directed flange.

The machine comprises essentially a coating and draining unit 10 and acuring unit 12, extending parallel to each other and spaced apart asseen in FIG. 2. An endless carrier chain 14 extends through these andother units of the machine as indicated in broken lines, being driven bysprocket wheels 16. These (or a suitable number of them) are driven by amain drive motor 18 mounted on top of the machine.

The chain 16 enters the coating and draining unit 10 where indicated at20 in FIG. 2, from a rinsing and drying unit 20 extending at rightangles to the units 10 and 12. At the end of the housing containing therinsing and drying unit remote from the coating and draining unit 10, isa loading unit 22 which receives containers 2 from a feed conveyor 24.The coating and draining unit basically comprises a "dry" section 26followed by a "wet" section 28, flow of liquid coating material withinthe unit 10 being confined to the "wet" section 28. The carrier chain 14extends through the front part of the "dry" section 26 and into the"wet" section, where it passes through a coating station 30 beforecrossing the unit 10 to pass in the reverse direction through the rearpart of the unit. There is thus a considerable length of chain betweenthe exit end of the coating station 30 and the point at which the chainleaves the "wet" section. The part of the unit 10 traversed by the chainbetween these points is the draining section of the coating and drainingunit.

Shortly after leaving the "wet" section, the chain passes through aprimary base wiping unit 33, whence it enters the curing unit 12. Thisconsists of a hot-air type oven designed to cure the coating on thecontainers at a closely-controlled temperature. Air is supplied by a fanunit indicated at 34, and is extracted by ducts 36. The chain 14 makes adouble pass through the curing unit 12, which is provided with asecondary base wiping unit 38 at the inlet end of the second or rearwardpart of the unit.

On leaving the curing unit, the chain passes through an unloadingstation 40 at which the containers are released to an exit conveyor 42.From the unloading station, the chain passes back into the loading unit22. The latter is of generally known construction, having a helicalfeed-screw device (not shown) which feeds each container 2 in turn fromthe feed conveyor 24 to a first transfer turret 44, from which thecontainers are transferred via a second transfer turret 46 ontorespective holders (not shown in FIGS. 1 and 2). The holders aresuspended from the carrier chain 14 in a manner to be described below.

Thus the containers are loaded in succession onto the carrying means,the chain 14 of which is in continuous movement at constant speed; andthe containers are then rinsed and dried in the unit 20, after which theliquid coating material is applied as they pass through the coatingstation 30. Excess material drains from the containers in the remainderof the "wet" section 28 of the coating and draining unit 10, thoughthere may be some remaining accumulation of material on the base of eachcontainer. This is removed by the primary base wiping unit 33, followingwhich the coating is cured in the oven 12, any final excess of coatingmaterial on the base of the container being removed by the unit 38.

The various units of the machine are constructed in the form of simplerectangular modules having a frame, not shown except in certain Figureswhere parts of the frame are relevant to understanding of the invention,and clad with removable panels 48, not shown except in FIG. 1 and 2.

FIG. 3 and 4 show the interior of the coating and draining unit 10 ingreater detail. The carrier chain 14 is suspended from a fixed endlessrunway (which extends the whole length of the chain as seen in FIG. 2),the runway 74 being fixed to a beam 50 secured to the main frame of themachine. FIG. 4 shows some of the containers 2, carried by holders 52which are suspended from the chain 14.

The "wet section" 28 of the coating and draining unit has a lower draintray 54, of structural material such as polypropylene, extending thefull length of the wet section. Above the lower tray 54, but below thecontainers 2 being carried through the unit, there is a main drain trayor "lake" 56, of the same material as the lower tray 54 and alsoextending the full length of the wet section. The coating station 30lies wholly over the lake 56, into which liquid coating material notretained as coating on the containers falls with a minimum of turbulenceor splashing, both at the coating station and in the subsequent drainingsection. The lake 56 has a cut-away portion at the corner farthest fromthe coating station. This cut-away portion is provided with a weir 58(which is shown more clearly in FIG. 24). The weir drains through a tundish 60 into a bulk weighing tank 62, which will be described more fullywith reference to FIGS. 23 and 25. The main supply of liquid coatingmaterial, held in a header tank 64 (FIGS. 1 and 2), passes via anormally-closed stop valve 66, FIG. 1, via a feed pipe 68 into the lake56 when the valve 66 is open: thence it passes over the weir 58 into thebulk weighing tank 62. The lake 56 has a drain 70 with a normally-closeddump valve 72, to drain into the lower tray 54 when necessary.

Reference is now made to FIGS. 10 and 12, which show the coating stationin detail. The chain runway mentioned above, fixed to the beam 50, isindicated at 74 above the chain 14, which is carried by the runway via aseries of chain hangers 76 each freely movable along the runway by meansof rollers 78. The chain hangers 76 are equally spaced along the chain.Attached to the opposite, i.e. lower, side of the chain below each ofthe chain hangers, there is a pivot bracket 80, to which a holderbracket 82 is pivoted on a horizontal axis. One of the holders 52 isitself secured to each of the brackets 82.

Each bracket 82 has an extension 84 carrying a freely-rotatable followerroller 86. At the coating station, as seen in FIG. 10, the roller 86engages a rail 88 (the coating control rail), which is fixed to the mainframe as diagrammatically indicated at 100 in FIG. 3. Roller 86 engagesrail 88 by gravity, because the axis 90 of the holder 52 and of thecontainer 2 carried by the latter is tilted as shown, by an angle ofless than 90° to the vertical centre plane 102 of the chain 14. In thisattitude, an O-ring 92, which is part of the holder 52, is frictionallyengaged by a traction bar 94, extending through the coating station asseen in FIG. 12. The traction bar 94 is mounted by brackets 96 to thebeam 50, but is carried by the brackets 96 via springs 98 which bias thebar 94 toward the holder 52.

A rigid mounting bracket 104 is secured to the main frame 100 andextends downwardly. At its lower end the bracket 104 has secured to itthe rear end of a stainless steel curtain plate 106, which extendstoward the centre plane 102 of the carrier chain and is curveddownwardly to a terminal edge 108, which is bevelled to a fine edge. Ascan be seen from FIG. 10, the edge 108 of the curtain plate is veryclose to a point on the outer surface of a container 2 passing throughthe coating station 30, in or just below the neck 4 of the container.Preferably the lateral position of the curtain plate is adjustable, forexample by means of its mounting screws 110. The vertical position ofthe curtain plate may also be made adjustable, by any suitable means(not shown).

The bracket 104 also carries an adjustable tube clamp 112 which holds anozzle 114. This is the nozzle that delivers the coating material to thecontainers. It is connected to the bulk weighing tank 62 via a feed pipe116 shown diagrammatically in FIGS. 3 and 4, the coating material beingdelivered to the nozzle by a feed pump 118 and variable control valve126. The latter are shown diagrammatically in FIGS. 4 and 25: it will beunderstood that the positions in which they are shown mounted are notdefinitive but that the pump 118 and control valve 126 may be in anyconvenient locations.

The nozzle 114 may have a baffle plate 120 just behind its mouth. Thenozzle mouth is arranged (by suitable adjustment of the tube clamp 112)preferably to be in actual contact with the rear surface 124 of thecurtain plate, as seen at 122, but not of course over the wholeperiphery of the nozzle mouth. A gap 128 must be left for the coatingmaterial to escape from the nozzle. If however the point of contact 122of the nozzle mouth with the curtain plate is at the top of the formeras shown, the material will emerge downwards and sideways, impinging onthe reare surface of the curtain plate and spreading out over thelatter. It then runs down the plate, so as to leave it in the form of acurtain of liquid depending from the lower edge 108 of the plate 106.Such a curtain can be seen at 130 in FIGS. 10 and 12. Thecharacteristics of the curtain 130, such as width, thickness,parallelism and so on, are determined by suitable adjustment of the flowvelocity by means of the main flow control valve 126.

Reverting to FIG. 3, there is shown a sensing rail 132 preceding thecoating control rail 88 in the direction of motion of the chain 14. Thesensing rail 132 is shown more clearly in FIG. 5. It is fixed to themain frame of the machine. Its purpose is to cause the containers 2 totilt into the attitude shown in FIG. 10. The rail 132 has a lead-inportion 134 parallel to the centre plane 102 of the chain, leading via adiverting portion 136 to a second parallel portion 140. The latter leadsvia a further portion 142 of the rail to a transfer portion 144, againparallel to the plane 102. The transfer portion overlaps a short part ofthe coating control rail 88.

In FIGS. 6 to 8, the action of the sensing rail 132 is illustrated. FIG.6 shows a container 2 at the point where it makes its initial contactwith the diverting portion 136, which tilts the container outwardly tothe attitude seen in FIG. 7, in which it is supported by the middleportion 140 of the rail 132. As the container then rides along theconverging portion 142, its angle of tilt is reduced to that shown inFIG. 8, so that when it leaves the downstream end of the transferportion 144, the roller 86 smoothly becomes fully supported by thecoating control rail 88. If, however, the holder 52 is empty of acontainer as shown in FIG. 9, it misses the sensing rail and remainswith its axis vertical throughout its passage through the coatingstation. In this way the holder 52 is kept away from an splashing ofliquid coating material.

The construction of one of the holders 52 is shown in FIGS. 13 and 14.Basically it is of extremely simple design, comprising only twostructural components, namely a body 146 and a plunger 148. The body isof "mushroom" form comprising a flat disc-like base 150 having a seriesof downwardly-depending, integral lugs or claws 152. Each claw 152 is oftriangular section (see FIG. 14) and has an outwardly-facing profilefitting behind the neck 4 of a container 2. The body 146 is made of aresilient plastics material such as a structural polyamide (Nylon), andhas a hollow stem 154 with a circumferential groove which hold theO-ring 92 previously mentioned. The stem 154 is secured rotatably in ahole in the holder bracket 82 by a circular spring clip 156. The plunger148 is also of mushroom form, but is of metal such as steel, Itcomprises a simple disc-like head 158 having triangular notches toaccommodate the claws 152. The head 158 is of approximately the samediameter as the body base 150, and has an integral stem 160, slidablefreely up an down the bore of the body stem 154 and having its top endexposed for engagement with a knock-out ramp 162 shown in FIG. 18.

Referring to FIG. 18, the ramp 162 is fixed via brackets 164 to the beam50 at the unloading station 40 (FIG. 2) of the machine. As each of theholders 52 carrying a container 2 reaches the ramp 162, and passes belowit, the ramp forces the plunger stem 160 of the holder downwards so thatthe plunger 148 forces the container out of the holder.

The bulk weighing tank 62, as shown in FIGS. 23 and 25, is part of anautomatic batch weighing system which ensures that there is a continuoussupply of liquid coating material to be pumped to the coating station30. The bulk tank 62 is mounted on a tilt plate 166 having a projectingportion 168 at one end, on which in this example the pump 118 is shownmounted. The tilt plate 166 is mounted at one side on a pair of heavypivots 170. On the other side, the tilt plate projects beyond the bulktank as shown at 172, this projecting portion being resilientlysupported as for example by a set of compression springs 174. Thesprings 174 and the pivot blocks 170 are fixed on blocks 176 which liein the lower drip tray 54 and are secured to the mainframe 100 of themachine.

As already described, the bulk tank 62 is supplied with liquid coatingmaterial from the weir 58 of the lake 56, via tun dish 60. Then thelevel of liquid in the tank 62 falls below a predetermined minimum, theweight of the tank becomes insufficient to keep the spring 174compressed, so that the tilt plate 166 rises and operates suitableelectrical switching means (not shown), to activate an alarm indicatinga need for recharging the tank 62. This is done by opening the valve 66,FIG. 1. The switching means may alternatively be arranged to actuatemeans for automatically opening the valve 66, suitable means beingprovided to ensure that it is re-closed when the level of liquid in thetank 62 reaches a predetermined maximum permitted value, and thatattention is drawin to the need for recharging the header tank 64, FIG.1.

In operation, with the carrier chain in continuous forward movement anda continuous, controlled flow of liquid coating material at the coatingnozzle 114, the containers pass in succession through the curtain ofcoating material 130 as seen in FIG. 10. The fine edge 108 of thecurtain plate and its proximity to the surface of the container, withcorrect adjustment of the liquid flow to give even distribution ofliquid across the curtain, enable the coating to be applied up to aprecisely-defined height (indicated at 178 in FIG. 10). The container isrotated at least twice, and preferably three times, by engagement of thetraction bar with the O-ring 92 while the container is in contact withthe curtain 130.

The arrangement shown in FIG. 11 differs from that of FIG. 10 in havingthe coating control rail, here indicated by the reference numeral 180,on the same side of the holder bracket, 82, as the traction bar. Thelatter, indicated at 184, is carried, with the rail 180, by the samemounting brackets 184 secured to the beam 50. The roller 86 is carriedon a short trunnion projecting from the bracket 82.

When the curtain 130 of liquid coating material is formed, there cantend to be surplus liquid at the outside edges of the curtain. This maycause or be associated with turbulence in the liquid. Turbulence must beavoided if the correct evenness of coating and precise location of theupper level (178, FIG. 10) of the coating are to be achieved, i.e.surging of liquid coming into contact with the container surface is tobe avoided.

The modified curtain plate 186 shown in FIGS. 19 and 20 overcomes thisproblem if it occurs. The plate 186 has its ends cut away at an angle tothe horizontal as shown, and this tends to spread the liquid at theouter edges of the curtain over the inclined parts 188 of the bottomedge 190.

Referring now to FIGS. 15 to 17 and FIG. 21, these show modificationsfor the coating of a container such as a PET bottle 191, FIG. 21, havinga narrow neck. FIG. 17 shows another article having a narrow neck. InFIG. 21, the curtain plate 106 is the same as in FIG. 10 for awide-mouthed container, but the bottle in this example is not tilted,hanging vertically instead as it passes through the coating station.Under these circumstances, provision of a sensing rail, coating controlrail and a follower roller such as the rollers 86, is unnecessary. Theholder 192, for a narrow-mouthed container comprises a simplecombination of a generally-cylindrical body 194 of the same or similarresilient material as the holder body 146 in FIG. 10, and amushroom-type plunger 200. The body 194 has integral,downwardly-depending resilient clases 196 which grip the container neck,198, externally. The plunger 200 has a head 202 in the form of a simpledisc of smaller diameter than the internal diameter of the claws 196,but functioning in exactly the same way as already described for theplunger 148 of FIG. 10.

Because the holder 192 is not required to tilt, the traction bar 94 ishere mounted for resilient movement horizontally to engage the O-ring92, again mounted around the holder body, so as to rotate the holder andthe container carried by it as the latter passes through the curtain ofcoating material. The holder 192 is secured by a spring clip 204 to arigid bracket 206 which is rigidly carried by the carrier chain 14 asseen in FIG. 21.

In FIG. 21, the coating level, i.e. the upper edge of the coating, isshown at 208. If this level must be higher, it is possible to modify theshape of the curtain plate so that its lower edge can be located belowthe flange shown at 210 around the neck of the bottle. Suchmodifications can be made whenever it is inappropriate for the simplecurved design of curtain plate 106 to be used, provided there are nosudden changes in profile such as to cause local turbulence in theliquid. It is also preferable that the lower edge of the curtain platebe directed downwardly.

In FIG. 22, by way of example, the coating level 212 is higher than thelevel 208 in FIG. 21, and the curtain plate, 214, has a modified profilewhich is S-shaped in cross-section, leading to a short downward section216 which terminates in the bottom edge 218.

Referring now to FIGS. 26 and 27, although (as has been seen from FIG.9) the holders 52 can be arranged so that they will only tilt towardsthe source of liquid coating material if loaded with a container, it maybe desired to ensure that an empty holder is as far away as possiblefrom the danger of contamination by the coating material. This can beachieved by the provision of an empty holder diverting rail 200, fixedto the main frame of the machine by suitable means and having a lead-inportion 222 which is so placed that its side 224 opposite to thevertical centre plane 102 of the carrier chain will be engaged by thefollower roller 86 of an empty carrier 52, but not by that of a carrierbearing a container. The lead-in portion 222 is therefore placedparallel with the central parallel portion 140 of the sensing rail. Thediverting rail 220 is shaped as seen in FIGS. 26 and 27, so that itcauses the empty holder 52 to swing away from the curtain plate 106.

There may be more than one coating station, using the plate curtainmethod described herein, suitably arranged to apply an appropriatenumber of coatings to the containers.

The technique of tilting the containers by means of the sensing rail,i.e. in response to the presence of the container, may be employed incoating machines in which the liquid coating material is applied byspraying or other known means instead of by the "curtain" methoddescribed above. Tilting assists the draining of excess material fromsome shapes of container; it also facilitates the application of acoating, for example by a localised spray head, to the underside of acontainer is such is required. This is particularly useful if thecontainer has a re-entrant base. Again, if the container is of non-roundcross-section, such as oval, the use of tilting makes easier theapplication of the coating by methods other than the "curtain"technique, as well as when this technique is itself chosen.

Referring now to FIG. 28, this shows another type of holder, 300, forinternally gripping a hollow container 302 or other hollow article. Thecontainer 302 here shown is a plastics vessel having a cylindricalsidewall 304 without any shoulder or flange to be engaged supportably bythe holder. The holder 300 can be mounted in a bracket 82 suspended fromthe chain conveyor in the manner already described; only the bottomplate of the bracket is shown in FIG. 28. The holder has a carrying head304 comprising a mushroom-type member 306, with a generally cylindricalbase 308 and an upstanding stem 310 carrying an O-ring 312 serving thesame purpose as the ring 92 in FIG. 10 or 11; a clamping plate 314coaxial with the base 308; and a peripheral, soft rubber grip ring 316sandwiched between the base 308 and plate 314. The stem 310 has acentral bore containing a rod 318 which carries a nut 320 bearing on theplate 314. The rod is biassed upwards by disc springs 322 bearingthrough a bush 324 on the top of the stem 310, so as to compress thegrip ring 316. The bore of the ring 316 is restrained by a shoulder ofthe base 308, so that when thus compressed it presses radially againstthe vessel sidewall 304 to hold the vessel 302 frictionally withsufficient force to prevent it from becoming dislodged during its travelthrough the coating machine. This force can be adjusted by means of thenut 320, which is secured by a locknut.

When the holder 300 reaches the cam plate 162 (FIG. 18) the cam plateforces the rod 318 to relieve the grip ring and allow the vessel 302 tofall. A similar cam plate (not shown) is provided at the loading unit 22to depress the rod 318 when the holder is introduced to the vessel 302.

Another holder is shown in FIGS. 29 to 31, at 330. The holder 330 has acylindrical body 332, rotatable freely in a cylindrical member 333 332,rotatable freely in a cylindrical member 333 fixed to the bracket 82 andhaving a hollow bore through which a plunger 334 slidably extends. Theplunger is biassed upwards by disc springs 335 and has a circumferentialrebate 336 to engage a springloaded ball 338 which normally holds theplunger in the upper position shown in FIG. 30. Below the body 332, theplunger 334 carries a circular stop plate 340, having a terminal,annular lower stop surface 342 to engage the top end of the container 2;and a clamping block 334 having a frusto-conical peripheral uppersurface 346. The block 344 and plate 340 are clamped together on theplunger 334, to move up and down with the latter. Within an annularrecess in the stop plate 340, a ring 348 is axially slidable. The ring348 is secured, through a hole in the plate 340, to the body 332, andcarries a peripheral rubber sleeve 350.

In the upper position of the plunger 334, the clamping surface 346forces the rubber sleeve against the inside surface of the container 2,to trap the end flange of the latter against the stop surface 342. Whenthe plunger is forced downwardly (e.g. by the cam plate 162), the sleeve350 is released as in FIG. 31.

FIG. 29 shows the stop plate 340 with a peripheral knurled surface toengage the rotation guide 94 in generally the same manner as the rubberO-ring 92 in FIG. 10, to rotate the holder 330.

Referring now to FIGS. 32 to 36, yet another holder 360, is againsuspended from the chain 14 by a bracket 82 (pivoted as before to abracket 80 secured to the chain). The holder 360 comprises a core block362 fixed to the bracket 82 and surrounded by a holder body 364 which isfree to rotate on the core block. The body 364 has three equi-spacedradial recesses 366 each accommodating a sprag 368 having a slot 370 toengage the end flange of a container 2. Each sprag 368 is held in itsrecess 366 by a common top plate 372 and a circumferential, resilientO-ring 374 which rests in a circumferential groove in the body 364. Theslot 370 of each sprag is central on a camming portion 376 of the spray.A generally cylindrical internal chuck member 378, having a radial topflange 380, is carried below the holder body 364 by a central rod 382,biassed upwardly by a compression spring 384 to the normal position seenin FIG. 32.

In operation, the container 2 is engaged with the holder 360 at thetransfer turret 46, FIG. 2, by being pushed upwardly so that thecontainer end flange forces the sprags outwardly as shown in FIG. 33,against the inward radial force exerted locally by the O-ring 374. Whenthe flange engages in the slot 370, the sprags return to their normalposition, FIG. 34, and remain there until the camming plate 162, FIG. 18forces the rod 382 downwardly. This cause the flange 380 of the chuckmember to engage the camming portions 376 of the sprags to re-open them(FIG. 35) and so release the container 2. As seen in FIG. 36, the O-ring374 may conveniently be used to engage the rotation drive rail 94 torotate the holder and the container 2 at the coating station.

In the holder shown in FIG. 37, a cylindrical holder body 390 has a stem392 which may be rotatably mounted in a bracket 82 (not shown) forrotation, and tilting if required, in the same manner as the holdershown in FIG. 13. Alternatively, rotation can be effected using anO-ring 394 around the body 390 itself. A carrier pad 396, profiled toengage the end flange of the container 2 as indicated in phantom lines,is carried below the body 390 by a rod 398 which can be spring-biassedupwards in the same manner as the rod 382 in FIG. 32, for example, Threespring steel pawls 400 are spaced equally around the inside of a skirtportion 402 of the body 390 to engage below the container flange andhold it against the pad 396. The container 2 is engaged with the holderby being pushed up so that the container flange becomes supported bydimples 404 of the pawls 398, and is released when the camming plate162, FIG. 18, forces the rod 398 and pad 396 down so that a peripheralcamming portion 406 of the pad engages an upper portion 408 of the pawlsto open them and allow the container flange to fall past the dimples404.

Referring now to FIG. 38, the chain 14 carries a bracket 420 in which apivot pin 422, extending parallel to the path of the chain 14, issecured. A holder assembly 424 for a container 2 is suspended from thepin 422 so as to be tiltable laterally. The holder 424 comprises acentral axle 426 and the parts carried directly or indirectly by theaxle 426.

This central axle is generally cylindrical. The top end of the axle hasa pivot head 428 carried by the pin 422, and a flange 430 against whichthe top end of a chuck 432 bears through a top bearing bush 434. Thechuck 432 has a hollow cylindrical stem 435 extending upwardly from anintergral bottom chuck body 436, and is rotatable freely on the axle426, on which it is mounted through the bush 434 and a bottom bearingbush 438.

The chuck stem 432 has axial splines 440, upon which are carried,reading downwards in FIG. 38, an upper guide roll 442, a radial bearing444, a thrust washer 446, and a pressure plate 448. A release roll 450having an enlarged bore engages on the underside of the thrust washer446, and is supported on the pressure plate 448 by three equally-spacedballs 452, normally engaged in conical seatings in the release roll 450and pressure plate 448. A reaction roll 454 is freely rotatable on theradial bearing 444. The upper surface of the chuck body 436, seen at456, is surmounted by a coaxial, annular lower roll 458, secured to thechuck body by means not shown, so that the lower roll and the chuck 432form a single unit, in which a number of radial recesses 460 are formed.In each recess 460 a bell crank 462 is pivoted, as at 464, in a splitbearing 466 comprising bearing halves formed in the lower roll 458 andchuck body 436 respectively. In the right-hand one of the two recesses460 visible in FIG. 38, the bell crank has been omitted for clarity.

Each bell crank 462 has a lower radial claw 468 to engage below the endflange of a container 2, and a radial arm 470 upon which there rests aspigot 472 of the pressure plate 448. The radial arm 470 is itselfnormally biassed upwardly by a compression spring 474 carried on a postintegral with the chuck body 436. This hold the bell cranks in theirnormal or container-engaging position shown in the Figure, and alsoholds the pressure plate 448, through the balls 452, against the releaseroll 450. Suitable means, not shown, are provided for retaining therelease roll, the bearing 444 and the upper guide roll 442, located intheir axial positions with the roll 442 bearing, rotatably through a topthrust pad 476, against an upper ring 478 fixed to the axle 426.

During movement of the holder 424, carrying a container 2, through thecoating machine, it is maintained in the required lateral orientation(vertical as shown, or tilted) by three-point lateral support providedpartly by a groove guide rail 480 against which the upper guide roll 442is freely rotatable, and partly by the drive rail 94 (for example aspreviously described), which engages the outside of the lower roll torotate the lower roll, chuck 432 and container 2. The lower roll, thechuck, and the other parts of the holder assembly rotatable with them,constitute the holder for an article such as the container 2. The thirdelement providing three-point lateral support is a reaction rail 482which is engaged by the reaction roll 454 to provide mechanical reactionagainst the driving force between the drive rail 94, and lower roll 458.At the unloading station 40 (FIG. 2), there is a fixed release rail 484,which has a camming action to force the release roll 450 laterallysideways, thus driving the balls 452 downwards to open the bell cranks462 through the pressure plate 448. A similar rail is provided at theloading station 22, FIG. 2, this time to restore the release roll to itscoaxial position when a container 2 has been introduced against thechuck body 436.

Reference is now made to FIGS. 39 to 44, which illustrate a coatingmachine generally similar to that already described except that it isadapted by the addition of an auxiliary coating station for applying acoating to that part of the recipient surface of the articles which isnot coated by application of the coating material at the coating station30, which in the context of FIGS. 39 to 44 will be called the maincoating station.

Referring to FIGS. 39 and 40, the auxiliary coating station is indicatedat 500, upstream of the section 26 of the machine, which is now notstrictly a "dry" section since containers wet with some coating materialwill pass through it. The main drain tray (or lake, or pan) 56 isextended so as to lie under the whole of the auxiliary coating station500 and the section 26. The station 500 has a supply nozzle 512 forsupplying the coating material for use at that station. The nozzle 512is itself supplied, for example through a branch pipe 513, from the samefeed pipe 116 as is the nozzle or jet at the main coating station 30.Thus both stations share a common coating material supply system and acommon draining and recirculating system for excess coating material,which is allowed to fall freely and without obstruction from theauxiliary coating station into the lake 56 (see 578 in FIG. 44).

In FIGS. 42 to 44, the articles being coated are shown, purely by way ofnon-limiting example, as being the same containers 302 as shown in FIG.28, the holders illustrated in FIGS. 42 to 45 all being, again by way ofnon-limiting example, the holders 300 of FIG. 28. At the auxiliarycoating station, a band of coating material is applied around theaxi-symmetrical, endless upper portion 580 of the outer or recipientsurface of the sidewall 304 of each container 302.

At the coating station 500, a mounting plate 508 secured to the machinemain frame 100, carries two bearing blocks 540, 542 in which a pair ofpulley shafts 544, 546 respectively are fully rotatable on verticalaxes. The lower end of the shaft 544 carries a belt pulley 505, and thatof the shaft 546 a belt pulley 506. The upper end of the shaft 544carries a pulley 510 which is driven through a drive belt 511 by anotherpulley, coupled to a donor belt drive motor 509.

A donor belt 504 extends around the belt pulleys 505 and 506, and has astraight working or coating course 548 parallel to the chain 14 andrunning so as to be engaged by the containers 302. The opposite courseof the belt 504, indicated at 550, has a nozzle or jet 512 arranged todirect a stream of liquid coating material (supplied from a source notshown) against the outer or donor surface 552 of the belt 504.

The donor belt 504 has to be kept under suitable tension, to which endany convenient tensioning device may be used. That shown in FIGS. 42 and43 comprises a pair of compression springs 554 bearing at one end on athrust block 556 mounted on the plate 508. The other ends of the springs554 engage the bearing block 542, which is mounted in an elongated hole558 in the plate 508 so that its axis is laterally translatable underthe control of the springs 554.

A back support device 560 may be provided behind the working course 548of the belt, to provide a positive, controlled lateral reaction forcefor engagement of the belt 504 with the containers 302. In this example,the device 560 comprises a frame 562, carrying a set of free-runningrollers 564 and urged toward the belt 504 by resilient elementsindicated diagrammatically at 566, which may be mechanical springs orfluid-pressure devices that may be made controllable so as to vary thepressure applied and thus the force exerted by the device 560.

The donor belt 504 may take any convenient form. It should be strongenough to withstand normal forces met in use, and to this end it may beof laminated construction with a resilient outer layer mounted on astout backing layer, which is impervious to penetration by the coatingmaterial and is typically of a drive belt material. The outer layer, orthe belt itself if unlaminated, is resilient enough to conform, as shownat 574 in FIG. 45, to significant changes in contour of the article 516,being coated. Whether or not the belt is of laminated construction, thedonor surface 552, on the outer side of the drive belt, is of a texturecapable of holding an even film of the coating material, but thematerial of which it is made should not be absorbent of the coatingmaterial (otherwise the latter, on drying, will clog and stiffen thebelt).

In operation, as the chain 14 is moved forward at constant speed toconvey the containers 302, they are brought into contact with the donorsurface which is being driven at constant speed along a parallel path asindicated by the arrow W in FIG. 42. The containers 302 are kept incontinuous rotation by engagement of the O-rings 312 of the holders 300with a rotation drive rail 538 is shown resiliently mounted in the sameway as the rail 94 in FIG. 10. The nozzle 512 directs a continuousstream of liquid coating material 576 onto the back course of the belt504, excess coating material falling freely to the lake as alreadymentioned.

The belt 504 transfers a band of coating material to the upper portion580, the lower edge 581 of which, and hence the band width, isdetermined by the width of the belt 504 and the location of the upperedge of the container 302 across the width of the belt. The line 581 ispreferably just below the upper limit of the area to which coating isthen applied at the main coating station 30.

The donor surface 552 will accept an amount of coating material over agiven area of the surface up to the maximum which it is capable ofretaining. The weight of coating material transferred to a bottle can bepredetermined by, for example, providing an adjustable doctor blade 582,FIG. 42, in association with the belt 504.

In FIGS. 41 and 45, the axes 591 of the belt pulleys 505, 506 areinclined to the vertical. This may be adopted with or without tilting ofthe article being coated. FIG. 45 shows a container 516 tilted with itsaxis 518 non-parallel to the axes 591, because of the requirements ofthe profile of the upper portion 520 of this particular container. Theaxes may all be inclined at the same angle to the vertical. The belt inFIG. 45 applies a band of coating to the portion 520 having the samewidth as the belt and extending downwardly from the extreme upper end ofthe outer surface of the container.

The container 516 is tilted prior to being brought into contact with thebelt 504, by means of a fixed tilt bar 522, FIG. 41, generally similarto the tilt bar (sensing rail 132) already described in detail withreference to FIGS. 3 to 5. A coating control rail 524, general similarto the rail 88 of FIG. 3 and others of the Figures, maintains theinclined attitude of the container through the auxiliary coatingstation. If a different angle of tilt is not required at the maincoating station, the rail 524 can extend through the latter in place ofthe rail 88. If a different angle of tilt is required, a transfer rail526 to effect the change of angle can be provided between the twocoating control rails 524, 88.

We claim:
 1. A method of applying a coating over a non-horizontalrecipient surface of an article, comprising the steps of:directing asupply of liquid coating material against a back surface of a curtainplate so as to spread the liquid over the back surface to fall as acurtain from a lower edge of the curtain plate; effecting continuousrelative movement as between the article and the curtain plate, with thearticle closely in front of the curtain plate, such that the recipientsurface intersects the curtain; allowing the material to run freely downthe recipient surface and allowing excess material to drain freely fromit; and causing the coating so applied to dry on the recipient surface.2. A method according to claim 1, for coating an external recipientsurface which extends around the article, wherein the step of effectingrelative movement comprises simultaneously causing the recipient surfaceto intersect the curtain and effecting relative rotation as between thecurtain plate and the article, so as to present the recipient surfaceprogressively to the curtain.
 3. A method according to claim 1, forcoating an external recipient surface endless in cross-section anddefining an axis of the article, wherein the step of effecting relativemovement comprises simultaneously advancing the article along a pathgenerally parallel to the lower edge of the curtain plate to cause therecipient surface to intersect the curtain, and rotating the articleabout its own axis, the curtain plate being maintained stationary.
 4. Amethod according to any one of the preceding claims for coating anarticle in the form of a hollow vessel, comprising the preliminary stepof engaging the vessel from above with a holder, the step of effectngrelative movement being carried out with every part of the holderexposed outside the vessel being maintained above the level of the upperedge of the coating material vertically below it on the recipientsurface.
 5. A method according to claim 3, wherein the step in which therecipient surface intersects the curtain is carried out with the centralaxis inclined to the vertical.
 6. A method according to claim 5 in whichthe axis of the article is initially substantially vertical, the methodcomprising the further step of engaging the recipient surface itselfwith a tilting member to tilt the article to its inclined attitudebefore introducing the recipient surface and the curtain to each other,and maintaining the inclination of the central axis with respect to thecurtain until the article has left the curtain.
 7. A method according toclaim 5, in which the article is advanced towards the curtain plate withits axis substantially vertical, the method comprising the further stepsof engaging the recipient surface itself with a stationary tiltingmember prior to the article reaching the curtain, so as to tilt thearticle to its inclined attitude, and maintaining the inclination of thecentral axis with respect to the curtain until the article has left thecurtain.
 8. A method according to claim 1 or claim 3 or claim 7, whereinthe step of effecting relative movement as between the article and thecurtain plate is carried out with an upper portion of at least that partof the recipient surface facing the curtain plate located above thelevel of the lower edge of the curtain plate so that the upper portiondoes not intersect the curtain.
 9. A method according to claim 8,including the further step of applying a band of coating material overthe upper portion of the recipient surface before or after applying acoating by means of the curtain.
 10. A method according to claim 9,wherein the step of coating the upper portion comprises:directing astream of liquid coating material on to a moving donor surface of anelongate donor member while moving the latter continuously along a firstpath, so as to charge the donor surface with a predetermined quantity ofthe material; and effecting continuous relative movement as between therecipient surface and the donor surface so that the latter transferscoating material on to the upper portion of the former in said band. 11.A method according to claim 10, including the further step, prior tobringing the recipient surface into contact with the donor surface, oftilting the article so as to orientate the recipient surface to engagethe donor surface in a line of contact over the whole width of the band.12. A method according to claim 10, in which said donor member is in theform of an endless belt, the method comprising maintaining, while thebelt is in contact with the article, both the article in its rotationand the belt in motion in said first path.
 13. Apparatus for applying acoating over a recipient surface of an article, comprising:holding meansfor holding the article with the recipient surface in a non-horizontalattitude; a forwardly and downwardly curved curtain plate having agenerally horizontal, free lower edge; nozzle means for directing acontinuous supply of liquid coating material against the back surface ofthe curtain plate so as to spread the liquid over the back surface tofall as a curtain from its lower edge; means for effecting continuousrelative movement as between the article and the curtain plate suchthat, with the holding means and the article closely in front of thecurtain plate, the recipient surface will intersect the curtain when thenozzle means is operating; and drying means for drying coating materialapplied to the article by its contact with the curtain.
 14. Apparatusaccording to claim 13, for coating an external recipient surface endlessin cross section and defining an axis of the article, wherein theapparatus includes rotating means for effecting relative rotation asbetween the curtain plate and the article, so that the recipient surfaceis presented progressively to the curtain during such relative rotation.15. Apparatus according to claim 14, wherein the curtain plate isstationary, the apparatus including artcle-advancing means for movingthe article along a forward path past the curtain plate and generallyparallel to the lower edge of the curtain plate (whereby to effect saidrelative movement), the rotating means comprising a rotatable element ofthe holding means, to be coaxial with the article when an article isbeing held, and a cooperating driving element for rotating the rotatableelement about its axis throughout the advance of the article past thecurtain plate.
 16. Apparatus according to claim 13, wherein the drivingelement for co-operation with the rotatable element of the holding meanscomprises a drive rail extending past, and generally in front of, thecurtain plate, the drive rail being generally parallel to the forwardpath.
 17. Apparatus according to claim 16, wherein the drive rail ismounted in a fixed position save that it is biassed by resilient meanstowards the path of the holding means so as to exert positive pressureon the rotatable element of the latter.
 18. Apparatus according to claim16 including a tilting member associated with the forward path upstreamof the curtain plate, to engage the recipient surface itself whereby totilt the article and holding means into an inclined attitude with theaxis of the article inclined to the vertical, and a tilt guide memberfor cooperating with the holding means for maintaining the inclinedattitude throughout the advance of the article past the curtain plate,the holding means having a guide follower means for co-operating withthe guide member, and wherein the drive rail is so disposed as to engagethe rotatable element of the holding means when the holding means is inits said inclined attitude.
 19. Apparatus according to claim 15,including a tilting member associated with the forward path upstream ofthe curtain plate, to engage the recipient surface itself whereby totilt the article and holding means into an inclined attitude with theaxis of the article inclined to the vertical, and a tilt guide memberfor co-operating with the holding means for maintaining the inclinedattitude throughout the advance of the article past the curtain plate,the holding means having a guide follower means for co-operating withthe guide member.
 20. Apparatus according to claim 19, wherein thetilting member is a simple, fixed bar appropriately shaped to effecttilting and to cause the holder to engage the guide member. 21.Apparatus according to claim 19, wherein the tilt guide member is afixed rail extending parallel to the forward path.
 22. Apparatusaccording to claim 19, wherein the tilt guide member and guide followermeans are so disposed as to come into co-operation with each other onlyif an article held by the holding means has been tilted by the tiltingmember, so that the holding means fails to assume the said inclinedattitude unless holding a said article.
 23. Apparatus according to claim22, including further guide means for engaging guide follower means onthe holding means so as to deflect the latter away from the curtainplate, the further guide means being downstream of the tilting memberwith respect to the forward path and so disposed that it can only engageits associated guide follower means if the holding means has failed tobe tilted by engagement of an article held thereby with the tiltingmember, the further guide means being arranged to keep the holding meansso tilted away until it has passed the curtain plate.
 24. Apparatusaccording to claim 23, wherein the said further guide member is a fixedrail extending parallel to the forward path.
 25. Apparatus according toclaim 23, wherein a single guide follower means is provided on theholding means for engagement with either one of the guide members. 26.Apparatus according to claim 13, wherein the lower edge of the curtainplate is relieved in end portions thereof and horizontal between the endportions.
 27. Apparatus according to claim 13, wherein the lower edge ofthe curtain plate is formed on a downward lip joined by a forwardlyextending flange portion to a main, forwardly and downwardly curvedportion of the plate.
 28. Apparatus according to claim 13, wherein theholding means comprises a holder having a carrying head with integralresilient fingers depending therefrom, the fingers being so arrangedthat when resiliently deformed they define together an endless profilecorresponding to the profile of a portion of an article to be gripped bythe fingers and a plunger member mounted freely in the carrying head andreciprocable downwardly to eject the article from the holder, theapparatus including a plunger-engaging member for forcing the plungerdownwardly, downstream of the drying means.
 29. Apparatus according toclaim 28, wherein the carrying head has an upwardly-extending stemcarrying a coaxial friction ring which constitutes the rotatable elementfor rotating the holder.
 30. Apparatus according to claim 28 or claim29, wherein the resilient fingers are arranged in a circle so that saidprofile is circular.
 31. Apparatus according to claim 13, wherein theholding means are adapted to present to the curtain an article, therecipient surface of which is endless in cross section and defines anaxis of the article, in an inclined attitude to the vertical. 32.Apparatus according to claim 13, having a main coating station at whichthe curtain plate is located, an auxiliary coating station having bandcoating means for applying a band of coating material over an upperportion of the recipient surface not coated at the main coating station,and transfer means for moving holding means carrying the article betweenthe two stations.
 33. Apparatus according to claim 32, for coating anarticle of which the recipient surface, including said upper portion, isexternal and extends axi-symmetrically around the article to define acentral axis of the article, wherein the band coating means comprises:anelongate donor member having a donor surface defining the band width fortransferring liquid coating material to the recipient surface; nozzlemeans for directing a continuous supply of said material against aportion of the donor surface; donor drive means for continuously movingthe donor member to transfer the coating material applied by the nozzlemeans to a position for transferring the material to the article; androtating means for effecting relative rotation as between the donorsurface and the article, so as to present the upper portion of therecipient surface progressively to the donor surface during suchrotation.
 34. Apparatus according to claim 33, wherein the donor memberis sufficiently resilient to conform with changes in contour in the areaof said band on the recipient surface, whereby to make contact with thesaid area over the whole band width.
 35. Apparatus according to claim33, wherein the holding means are adapted to present to the donor memberan article, having its recipient surface extending externally andaxisymmetrically around the article to define a central axis, in aninclined attitude with its central axis inclined to the vertical. 36.Apparatus according to claim 33, wherein the donor member is an endlessbelt, the band coating means further comprising at least two beltpulleys, the belt extending around the belt pulleys to define asubstantially straight article-engaging course of the belt and a furtherbelt course adjacent the nozzle for receiving coating material from thelatter.
 37. Apparatus according to claim 36, wherein one of the beltpulleys is coupled with the donor drive means, another being mountedwith its axis translatable laterally under the control of resilienttensioning means whereby to induce sufficient tension in thearticle-engaging course of the belt.
 38. Apparatus according to claim33, wherein the curtain plate and the band coating means are in fixedlocations, the apparatus including article-advancing means for movingthe article along a forward path past the curtain plate and the bandcoating means (either before the other), the rotating means comprising arotatable element of the holding means to be coaxial with the articlewhen an article is being held, and a co-operating driving element forrotating the rotatable element about its axis throughout the advance ofthe article in contact with the donor member.
 39. Apparatus according toclaim 38, wherein the driving element for co-operation with therotatable element of the holding means comprises a drive rail extendingpast the band coating means and parallel with the forward path. 40.Apparatus according to claim 33, wherein the belt pulleys are mountedwith their axes inclined to the vertical, so that the article-engagingcourse of the belt is non-horizontal.
 41. Apparatus according to claim39, wherein the drive rail is mounted in a fixed position save that itis biassed by resilient means towards the holding means so as to exertpositive pressure on the rotatable element of the latter.
 42. Apparatusaccording to claim 38, wherein the driving element for co-operation withthe rotatable element of the holding means comprises a drive railextending past the band coating means and generally parallel to theforward path.
 43. Apparatus according to claim 42, wherein the driverail is mounted in a fixed position save that it is biassed by resilientmeans towards the path of the holding means so as to exert positivepressure on the rotatable element of the latter.
 44. Apparatus accordingto claim 38, including a tilting member associated with the forward pathupstream of the band coating means, to engage the recipient surfaceitself whereby to tilt the article and holding means into an inclinedattitude with the central axis of the article inclined to the vertical,and a tilt guide member for maintaining the inclined attitude throughoutthe advance of the article in contact with the donor member. 45.Apparatus according to claim 44, wherein the holding means has a guidefollower means for engaging the tilt guide member.
 46. Apparatusaccording to claim 44, wherein the tilt guide member is so disposed asto be operative only if an article held by the holding means has beentilted by the tilting member, so that the holding means fails to assumethe said inclined attitude unless holding a said article.
 47. Apparatusaccording to any one of claims 44 to 46, wherein the tilting member is asimple, fixed bar appropriately shaped to effect tilting and to causethe holder to engage the guide member.
 48. Apparatus according to anyone of claims 44 to 47, wherein the tilt guide member is a fixed railextending parallel to the forward path.